LIPO protector for brushed motors!

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stormer254
Posts: 91
Joined: 03 Mar 2018, 10:08

LIPO protector for brushed motors!

Post by stormer254 »

I have acquired a rather nice Aeronca with an Astro geared brushed motor that is set up for Nicads, is there anything available to protect the lipos I will use to fly it on? Google has not helped and struggling to find a 3/4s brushed speed controller for lipos. the plane has a Fleet brushed ESC and I would like to use it if possible, I buggered up a good lipo pack before flying a brushed motor plane! Any help and advice will be gratefully received
Steve
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Shaun
Posts: 1049
Joined: 15 Feb 2018, 21:49
Location: West Yorkshire

Re: LIPO protector for brushed motors!

Post by Shaun »

You will most likely be able to buy a new brushless motor and ESC for the cost of a lipo capable brushed ESC these days.

And you'll save a load of weight.

Shaun
Martin
Posts: 744
Joined: 16 Feb 2018, 14:11
Location: Warwickshire

Re: LIPO protector for brushed motors!

Post by Martin »

I just use one of the older brushed-motor ESCs that were designed to work on NiCads or NiMH. In my experience, they work fine with LiPo batteries. A 2-cell LIPo is pretty much the same voltage as a 7-cell NiCad pack, so I use 2-cell LiPos in planes that used to fly on 7-cell or 8-cell Nickel packs. The LiPos are much lighter, of course, and have much greater capacity if you choose one with about the same physical size as the Nickel pack it's replacing.

A three-cell LiPo is more equivalent to a 10-cell Nickel pack: I've never flown any brushed motors that used that high a voltage.

I have planes and helicopters that used to fly on 10-cell and 12-cell Nickel batteries, but they always had brushless motors from the outset. The old brushless controllers in them were designed for Nickel batteries, but I just substitute LiPo batteries in place without altering any of the ESC settings. I use 3-cell LiPos on the plane that used to fly on 10-cell Nickel, and 4-cell LiPos on the helicopter that used to fly on 12-cell Nickel. The 4-cell LiPo is a higher voltage than the 12-cell Nickel, but I checked the specs for the ESC and it said it could handle up to 16 Nickel cells, so it's fine. I adjusted the pitch curves so the helicopter doesn't pull too much pitch to overload the motor, now that the rotor speed is higher.

The older ESCs used to cut off or reduce power to the motor when they detected the NiCad battery running down, and I suspect that would still protect the LiPos too. But I always use a flight timer (or telemetry feedback of the battery voltage), and aim to land with the battery still having about 25% left. As with any electric model you should always land immediately if you notice the power beginning to sag.
stormer254
Posts: 91
Joined: 03 Mar 2018, 10:08

Re: LIPO protector for brushed motors!

Post by stormer254 »

Thanks for the replies, I already have ESCs and brushless motors in the shed that would power this plane but would like to use the original power set up, much as we like to use our original radios but would need to use my lipos, I went through the nicad, buggy motor, microswitch set up many years ago when electric flight was mostly just a dream and don't want to recreate that. My radio does not have telemetry, I have to fly a single stick with throttle conversion, a friend gave me a RC LI-PROTECTOR but research has shown this is for brushless motors assume from the time when the early ESC did not protect your lipo from over discharge. I was just hoping there would be something suitable/ similar for brushed motors. I have already converted another model, a twin, that came from the same source to brushless and lipo. I just would like to use the original Astro set up. Thanks once again for your advice and help!
bluejets
Posts: 316
Joined: 19 Jun 2019, 04:09

Re: LIPO protector for brushed motors!

Post by bluejets »

There are LiPo bms modules one can simply solder to LiPo or Li-ion cells if that is what you are after.

They cut out when battery voltage gets to a predetermined level.

Some modellers are using 18650 cells these days also and the bms modules are available for these as well.

Cost is minimal and size is small, with most mounted on the side of the cell.
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Mike_K
Posts: 669
Joined: 16 Feb 2018, 06:35
Location: Hertfordshire

Re: LIPO protector for brushed motors!

Post by Mike_K »

Hi Steve

You say you are having trouble finding a 3S/4S brushed ESC, but if it's the standard Astro 05 geared motor I wouldn't advise you to use a 3S or 4S Lipo, but take Martin's advice and use a 2S Lipo. My original Astro 05 was always run on either 7S or 8S NiMH, I don't think it would take more cells and a 2S Lipo is an equivalent voltage. If I remember it used to take around 35A and give around 300W and the standard Fleet FPS-36A ESC was a good match. If you can't find a suitable ESC, I've probably got a Multiplex 40A ESC that is NiMH/2S Lipo compatible in my spares box. Most Astro motors/ESC were as efficient as modern brushless motors, so if your Aeronca is under 5lb, it should fly fine with a 2S 2200mAH Lipo.

Mike
stormer254
Posts: 91
Joined: 03 Mar 2018, 10:08

Re: LIPO protector for brushed motors!

Post by stormer254 »

Thanks I will give it a try with 2S, I am away for a week now and will post up some photos etc when I return.
stormer254
Posts: 91
Joined: 03 Mar 2018, 10:08

Re: LIPO protector for brushed motors!

Post by stormer254 »

100_2528.JPG
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100_2531.JPG
A few photos of the Aeronca which also might be a Cessna!, she weighs 70 oz. complete less battery and has 700 square inches with a 70" span so certainly towards the floaty side, I don't possess any 2s lipos above 500 ma so have a few tired 2.2 3s or similar which I will use for test flying attempts and try not to use full throttle! If she flies as good as she looks I will definitely be happy to buy a couple of suitable 2s packs.

Blue jets, I have looked for the BMS type device you mentioned but cannot really find anything, if you had a link or source that would be very grateful, like I have said before, I was a builder in my other life so problem solving generally involved a lump hammer!
GarydNB
Posts: 282
Joined: 15 Feb 2018, 23:12

Re: LIPO protector for brushed motors!

Post by GarydNB »

My money's on it being an Astro Flight Porterfield Collegiate.
Gary
bluejets
Posts: 316
Joined: 19 Jun 2019, 04:09

Re: LIPO protector for brushed motors!

Post by bluejets »

Search for this on Ebay..... bms 18650

Example 1 ..... https://www.ebay.com.au/itm/12439684749 ... SwN3lckwqy

Example 2 ..... https://www.ebay.com.au/itm/17474954409 ... Sw91hbPC~V
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